Liquid cooled internal combustion engine

Abstract

A liquid cooled internal combustion engine, comprising: an integrally cast engine main body including a cylinder block, a cylinder head, and a crankcase skirt, a crankcase cover attached to an open end of the skirt to define a crankcase therein, a crankshaft extending vertically in the crankcase and rotatably supported by the skirt at its both ends, a camshaft rotatably supported by the cylinder head and extending in parallel with the crankshaft, a timing belt passed around pulleys mounted on lower ends of the camshaft and the crankshaft, respectively, and extending in a belt chamber defined in the cylinder block along a lower side of the cylinder bore; a cooling liquid jacket defined in the cylinder block along upper and lateral sides of the cylinder bore. The jacket may be formed during the casting process by pulling a core either upwards or toward the open end of the skirt. The cooling liquid may consist of the lubricating oil for the engine. Thus, a jacket for the cooling liquid can be formed without requiring its cylinder head to be cast separately from its cylinder block, and the rigidity of the part of the cylinder block adjoining its cylinder head can be increased without increasing its wall thickness. Also, a compact design of the engine is made possible, and the process of fabricating the engine can be simplified.